The 28-year-old heir ap parent to the Trump real- estate empire has been ousted from his own condo board in a coup d’état during which tenants al leged “arrogant” and “belligerent” behavior and dubious management practices by the board.

Trump Jr. was blindsided at a meeting on Nov. 8, when one angry resident wielding 150 proxy votes re placed the en tire seven- member board of 220 River side Blvd., one of seven swanky residences at Trump Place, daddy Don ald’s $3 billion Upper West Side development.

“They treated us with scorn – so it’s good riddance,” one ten ant told The Post.

Trump Jr. called the election “possibly fraudu lent” and told The Post he plans to battle back against the resident, Eugenia Kaye.

“I don’t like what happened,” Trump Jr. said. “What Kaye did was very underhanded.”

She “spun a tale about pur ported mismanagement” then “sought out those ten ants she thought would side with her,” he said.

Once they did, she asked them to sign a ballot containing the names of six additional board candidates.

“Most of those absentee voters thought they were voting for Kaye alone,” he said.

Kaye, wife of filmmaker Tony Kaye, was elected president of the board in the vote. She declined to comment.

Trump Jr., an executive vice president at the Trump Organization, moved into the building two years ago and has served on the board since 2003, when he was appointed by his dad.

In late October, Kaye hand-addressed letters to the owners of all 420 units, outlining a series of grievances.

She also urged them to attend the building’s Nov. 8 annual meeting to vote the board out while voting her in. Those who could not attend were asked to vote via proxy.

Among the gripes was the board’s requirement that tenants schlep across town to Trump headquarters to read the minutes from its monthly meetings, rather than having them e-mailed or available in the building, another tenant said.

“Even if we did go over there, they wouldn’t give us copies of the minutes. We had to read them in the office,” the tenant said.

There were also questions about an $80,000 line item in the management’s ledger categorized as “other” under “office expenses.”

The most irksome issue seemed to be the board’s handling of a recent $300,000 Con Ed bill, which it initially said were charges assessed on a faulty electric meter.

“A month later, they sent a second letter telling us it was for a broken gas meter,” said another tenant. “We never got the full story.”

Condo policy dictates that at least 51 percent of the tenants have to vote against the board to give it the heave-ho.

When only about 60 of the more than 400 owners showed up at the Nov. 8 meeting, Board President Paul Davis informed the group there was no quorum, another tenant said.

“That was when Kaye whipped out a stack of about 150 proxy votes – and Donnie Trump’s face went white,” the tenant said.